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The ultimate pressure in avacuum vessel is defined as a quotient between the total autgassing rate and pumping speed. In high vacuum and espacialli un UHV,the method for determination of outgassing rate and pumping speed becomes important since the pressure gauge may influence the result. It is well known that the hot ionization gauge may be a permanent gas source, while the processes on the cathode surface may comletely change the composition of the gas. In the paper, we show the influence of the quadrupole madd spectrometer, mounted in a well outgassed UHV vessel, upon the total pressure reading and residual gas composition. It was clearly shown that the hot cathode is the main source of gas. Končni tlak v posodi je določen s kvocientom hitrosti razplinevanja stene posode in hitrostjo črpalke. Z znižanjem tlaka postaja merilna metoda, s katero določamo hitrost rayplinjevanja posode ali črpalke, vse bolj pomembna. Poznano je, da so merilniki na vročo katodo izdaten vir plinov, procesi na katodi pa lahko povsem spremenijo sestavo plina. Za zgled navajamo meritev tlaka s kvadrupolnim masnim spektrometrom v predhodno dobro razplinjeni UVV-posodi, kjer je vroča katoda glavni vir plina.

During the last forty years, a great progress was noticed on the whole field of vacuum technique. To reach and accurately measure a pressure in te UHV region became obvious in many branches, while the preparation of UHV is more or less just a routine. The situation was not the same in the range of extremely high vacuum (EHV). The lowest record from tthe early sixties was matched again few years ago. EHV is still interested and reserved for the surface science, particle physics and the vacuum meteorology. In the present paper, some results of the studies of hydrogen outgassing are presented. The recombination limited model was used to be comfirmed as a limiting phase of hydrogen outgassing. Ten equal cells were made from steinless steel of thickness of 0,15 mm, volume 0,16 l and the inner surface area of 450cm2. During a controlled heat treatment cycle, they were pumped to UHV region (typically 5.10sup(-8) mbar), when the pumping tube was sealed-off. Even if the temperature and the duration of a bake out were relatively short the initial outgassing rate was typically below qsub(out) = 2.10sup(-14) mbar.l/cm2s. In seven cells, the presure and the pressure rise slope were measured again after some thousand hours. The total pressure was measured again and the composition of residual atmosphere was determined afterwards. Both results confirm the applied model. It is evident, that by applying the minimum thickness of the chamber wall, achieving and meintenance of UHV and EHV stainless steel chambers can be made cheaper and simplified. V zadnjih štiridestih letih se je vakuumska tehnika močno razvila. Doseči in meriti tlak v območju ultravisokega vakuum (UVV) je postalo v mnogih panogah nuja, zahtevnost priprave pa je le še laboratorijska veščina. Nasprotno pa je ekstremni visoki vakuum (EVV) kljub napredku ostal v mejah, ki so bile dosežene v začetku šestdesetih let. Zanim ostaja za področje raziskav površin osnovnih delcev in za vakuumsko meroslovje. V članku so predstavljeni rezultati lastnih raziskav, ki nam rabijo za potrditev oz. korekcijo modela, ki predstavlavlja rekombinacijo kot omejitveni mehanizem razplinjevanja vodika. Izdelanih je bilo 10 enakih celic z debelino stene 0,15 mm, prostornino 0,16 l in geometrijsko površino 450 cm2. V nadzorovanem termičnem postopku so bile izčrpane do meje UVV (5.10zgoraj(-8) mbar), nakar je bila črpalna cev hladno zavarjena. Tlak je bil nato merjen z merilnikom na vrtečo se kroglico (SRG) v obdobju od 24 h do nekaj tisoč ur. Hitrost raplinjevanja pa je bila kljub kratkemu pregrevanju že na začetku v vseh celicah v območju pod qspodaj(out) = 2.10zgoraj(-14) mbar.l/cm2s). V sedmih celicah sta bila po več tisoč urah tlak in hitrost naraščanja še enkrat izmerjena, nakar so bile celice pregrete v vakuumu za nekaj ur. Totalni tlak je bil izmerjen s SRG. V zadnji fazi pa je bila z masnim spektrometrom določena tudi sestava preostale atmosfere. Relativno velik delež vodika je potrdil pravilnost uporabljenega modela. Z izbiro minimalne debeline sten in predelavo obstoječih komponent je nakazana možnost za poenostavljeno in cenejše doseganje UVV kot tudi EVV.

Stainless steel with its unique mechanical properties is the most frequently used material for manufacturing chambers and components for ultrahigh vacuum (UHV). Its disadvantage is hydrogen outgassing which makes obtaining of UHV troublesome. Vacuum annealing and prolonged in situ bake out are applied methods to reduce the outgassing rate to acceptable level of ?$10^{-12}$?mbar.l/(s.?$cm^2$?). Theory of hydrogen putgassing based for decades on diffusion as limiting mechanism which completely failed when very low outgassing rates were required. Recombination limited outgassing was introduced recently and explains the required duration and temperature of bake out better than just diffusion limited theory. Measured values of recombination rate ?$K_L$? are scattered over orders of magnitude which shows the importance of surface composition and it's structure . The surface of stainless steel is covered with oxides and other deposits which persist normal cleaning procedure. In the paper, outgassing rates are given on the dimensionless scale of previous thermal treatment for reported range of reacombination coefficient ?$K_L$?. Numerical simulations of bake out with different values of D and ?$K_L$? are made in order to predict required procedure to obtain very low outgassing rates. Our diagrams enable to evaluate also the advantage of modern surface treatment methods as a replacement of prolonged vacuum bake out. Nerjavno jeklo je najpogosteje uporabljen konstrukcijski material za izdelavo posod, v katerih želimo ustvariti ultra visoki vakuum, (UVV). Žal pa intersticijsko raztopljen vodik, ki se sprošča iz kovine, otežuje doseganje UVV. Sprejemljiva jakost sproščanja z enote površine je v območju ?$10^{-12}mbar.l/(s.cm^2$?, kar dosegamo danes le s predhodno toplotno obdelavo v vakuumu. Teorija vakuumskega razplinjevanja je dolga desetletja slonela na teoriji difuzije. Zaradi popolnega neujemanja pri doseganju nizkih vrednosti razplinjevanja je bila v zadnjem času dopolnjena z upoštevanjem rekombinacije atomov vodika na površini, ki skupaj z difuzijo vodika iz materiala določa dinamiko sproščanja in s tem končni tlak. Izmerjene vrednosti rekombinacijskega koeficienta ?$K_L$? na različne načine obdelanih površin se razlikujejo za več velikostnih razredov. Velik pomen imajo sestava in struktura oksidov kot delež segregiranih primesi. V članku je prikazan vpliv ?$K_L$? na jakost razplinjevanja in doseženo stopnjo razplinjenosti med procesiranjem, ki ga lahko predočimo na brezdimenzijski časovni skali, ki velja sicer za difuzijo. Napravljena je računalniška simulacija razplinjevanjaza različna razmerja difuzijske konstante D in ?$K_L$?, kar omogoča enolično določitev prednosti posameznega postopka predobdelave, ki jih srečujemo zadnja leta v literaturi kot nadomestilo za dolgotrajno termično obdelavo v vakuumu.

High vacuum and ultra high vacuum technology depends crucially on tightness of vessels and components. The most sensitive methods developed to control and measure leakage were so called vacuum methods, where leakage is measured in evacuated vessel. Nowadays, high demands for tightness, comparable to those in high vacuum technique, are met in several other fields. In the paper, basic quantities and relations, necessary to describe pump-down process are described. Physical units for measuring leakage rates, which are closely related to difficulty range of particular application, are also introduced. Priprava visokega vakuuma je od vsega začetka zahtevala izredno dobro tesnost vseh elementov, zato so bile razvite tudi izredno občutljive metode preizkušanja in merjenja netesnosti. Danes srečamo enako visoke zahteve za tesnost še v mnogih drugih vejah tehnike, zato se vakuumske metode ob primernih prilagoditvah uporabljajo tudi tam. V prispevku so podane osnovne definicije količin in zveze, ki jih potrebujemo za opis črpanja in spremljajočih pojavov. Vpeljane so enote za merjenje netesnosti, kar je osnova za razvrstitev na območja zahtevnosti.

All metal vessels with which thermal insulating vacuum has to be preserved forsome years, must be prepared very carefully regarding cleaning and processing. Limits for leaking and outgassing are practically the same as for UHV chambers. Evacuatead panel, consisted from two metal foils supported by discrete supports can exhibit excellent thermal insulating properties. It's unusual shape, thin walls and local mechanical strain restrict conditions at vacuum processing. Preparation of test samples, pumped through tube with small conductance, is addditionaly troublesome. In the paper, basic vacuum demands, theoretical and practical limitations of material selection, cleaning, welding and pumping are given. Measured pressure rise slope of test samples is compared to literature data for thick wall chambers. Kovinske vakuumske posode, v katerih je treba zagotoviti termično izolativni vakuum vsaj nekaj let, zahtevajo izredno skrbno nadzorovane postopke priprave in procesiranja. Dopustno puščanje in razplinjevanje sten morata biti v razredu, ki ga sicer zahtevamo za UVV posode. Evakuirana izolativna plošča oz.panel, sestavljen iz dveh folij, med katerima je diskretno podporje, bi imela po izračunu izredne izolacijske lastnosti. Nenavadna oblika vakuumske posode, razmeroma tanka stena in lokalne obremenitve na mestih podpor so pri načrtovanju vakuumskega procesiranja resne zahteve. Pri pripravi vzorcev, posebno še, če smo jih namenili črpati po cevi z omejeno prevodnostjo, naletimo na dodatne težave. V članku so predstavljene osnovne vakuumske zahteve in teoretične omejitve, ki pogojujejo izbiro in pripravo materiala, postopkov izdelave tesnih spojev in procesa črpanja. Rezultati meritev naraščanja tlaka v preizkusnih panelih so prikazani v primerjavi z literaturnimi podatki za debelostenske posode.

Research of the vacuum as thermal isolation is described. Special concern is put on the invention of the Dewar's flask and it's use in Europe and USA. Opisujemo raziskovanje vakuuma kot toplotnega izolatorja. Posebno pozornost posvečamo odkritju Dewarjeve posode in njeni uporabi v Evropi in ZDA.

Next year we celebrate centoury from invention of cathode ray tube. In the first part of the article the history of the vacuum components of television before the predominance of electronics is described. Special concern is put on the research done by Slovenes. In the second part of this article the history of the cathode ray tube as a part of the tealevision is described. A special concern is put on the research done by baron Codelli, a Ljubljana-man of Italian origin. Prihodnje leto bomo praznovali stoletnico iznajdbe katodne elektronke. V prvem delu razprave opisujemo razvoj vakuumskih komponent za televizijo pred prevlado elektronike. Posebno pozornost posvečamo raziskavam avtorjev slovenskega rodu. V drugem delu razprave opisujemo razvoj katodne elektronke kot slikovne elektronke za televizijo. Posebno pozornost posvečamo raziskavam barona Codellija, Ljubljančana italijanskega rodu.

Stable operation of electro-optical system in high vacuum is mainly dependent on electrode surface condition. In strong electric field, several surface phenomena can arise: field emission, surface charging of dielectric particles, ionization and finally break down or arching. The most important step in electrode's surface preparation before switching on the high voltage is called conditioning, when surface defects, which are responsible for undesired phenomena, are destroyed. All other manufacturing steps are nearly of same importance, starting from material selection, mechanical treatment and cleaning. Edges of electrodes, from which field emission have arised, were inspected by scanning electron microscope and electron microanalyzer after chemical etching. Microinclusions of titanium carbide were found which could be responsible for fied emission and inefficient high voltage conditioning. Some test electrodes were prepared with golden layer in order to diminish influence of carbide inclusions. Improved characteristics of high voltage gap were observed. Stabilnost delovanja elektro-optičnega (EO) sistema v visokem vakuumu je zelo odvisna od stanja elektrod. V močnem električnem polju pride lahko do pojavov hladne emisije (HE), kopičenja površinskega naboja na izolatorjih, ipd., kar privede v danem trenutku do preboja. Priprava elektrod za delovanje na predpisanih napetostih, t. i. kondicioniranje, je zadnja faza obdelave. Enako pomembne pa so zgodnejše faze izdelave. Poznan je vpliv izbire materiala, mehanske in kemijske obdelave površin in možen vpliv naključnih delcev na površini. Manj raziskano pa je vedenje vključkov izolatorjev, ki so nastali v zlitini ob metalurškem procesu. Robove elektrod iz nerjavnega jekla, ki jih nismo uspeli kondicionirati z visoko napetostno obdelavo, smo kemijsko pojedkali. Vključki, ki so postali na slikah, dobljenih z vrstičnim mikroskopom, razločno vidni, smo preiskali z elektronskim mikroanalizatorjem. Pokazalo se je, da je titanov karbid nastal pri izdelavi jekla kot dodatek za stabilizacijo ogljika in preprečitev interkristalne korozije. Njegove lastnosti nam pojasnijo težave pri kondicioniranju elektrod oz. nestabilno vedenje elektronsko optičnega sistema. Prekritje kritičnih delov elektrod z latom se je pokazalo za eno od sprejemljivih in dokaj uspešnih metod za odpravo pojavov, ki jih lahko povzročajo vključki.